Dissertation > Excellent graduate degree dissertation topics show

Bacterial Diversity in Rhizospheric Soils of Predominant Plants Growing in Copper Mining Wasteland and the Effects of Copper-resistant Bacteria on the Accumulation of Copper from Soil by Maize

Author: MaHaiYan
Tutor: ShengXiaFang
School: Nanjing Agricultural College
Course: Microbiology
Keywords: copper mining wasteland copper-resitant bacteria bacterial diversity plant-microbe remediation colonization
CLC: X53
Type: Master's thesis
Year: 2008
Downloads: 249
Quote: 0
Read: Download Dissertation

Abstract


Phytoremediation is an emerging as a cost-effective and environment-friendly technology for remediation of heavymetal-contaminated soils. However, phytoremediators, the plants used for remediation, often have a slow growthrate and produce limited amounts of biomass.Using chemicals to enhance phytoremediation is comparatively available but usually expensive and unfriendly to environment. Therefore, it is very important to search for a microbe-strengthened phytoremediation approach to enhance plant remediation economically and effectively.In this study, bacterial diversity of rhizospheric soils of predominant plants growing in copper mining wasteland was analyzed at first through Denaturing gradient gel electrophoresis （DGGE）. The results showed great diversity of heavy metal resistant bacteria in rhizospheric soils while no apparent microbe community structure differences were observed among different rhizospheric soils, with a similarity of more than 87%. Combining with traditional microbe isolating method of streak plating, 89 copper-resistant bacterial strains (Cu 50 mg·L-1) were screened out from 11 rhizospheric soil samples. Further more, 17 strains with higher copper resistance (Cu 200 mg·L-1) and copper-solubilizing ability were screened out by increasing Cu concentration gradually and Cu solubilization experiment. The analysis of 16S rDNA sequences of these 17 bacterial strains revealed abundant genetic diversities; copper solubilization experiments in solution culture suggested their functional diversities; the intrinsic ability for the production of ACC deaminase, IAA, siderophore, and so on, suggested the metabolic diversities among them. The results of the influence of temperature, pH, other heavy metals, antibiotics on the growth of the 17 strains also showed abundant diversities.Four strains JYC17, MT16, YAH27 and HQN2 were selected from the 17 strains with higher biomass, more acid production, more effectively copper solubilization, stronger survival ability and growth-promoting ability for further studies. Copper solubilization of the four strains was investigated in solution culture containing Cu2（OH）2CO3 and Cu（OH）2. The results showed that they could not only endure copper but also solubilize hardly-soluble copper. The pH value of liquid YN medium added with Cu2（OH）2CO3 and Cu（OH）2 in the bacterial inoculation treatments was decreased by 2.29 - 3.04 unit and 0.19 - 2.64 unit respectively, at the same time the concentration of available copper was increased by 136% - 402% and 103% - 218% respectively. Deeper studies showed that the organic acid produced by the four strains were different and copper could promote the production of organic acid. All the four strains could significantly increase the concentration of available copper in the soil （added Cu2（OH）2CO3 or added Cu（OH）2 or copper-contaminanted soil） compared to the control, HQN2 was the best and YAH27 was the second. After 10 days’ cultivation, the amount of inoculated bacteria reached 106 - 107 cfu·g-1 soil. As for the strong buffer capacity of the soils, the pH values of the inoculated soils only decreased a little compared to the control.JYC17-gfp, MT16-gfp, YAH27-gfp and HQN2-gfp with gfp marker gene were gained by tri-parental mating. Studies showed that the gfp gene could steadily exist in the labeled strains and did not affect their copper-solubilizing ability. Colonization experiment showed the labeled strains JYC17-gfp, MT16-gfp, YAH27-gfp and HQN2-gfp could not colonize in the inner root of maize, but could colonize on the surface of the root and could promote the growth of maize at seeding stage.The pot experiments demonstrated that the four strains JYC17-gfp, MT16-gfp, YAH27-gfp and HQN2-gfp could promote the growth of maize. Especially, strain JYC17-gfp had the best effects which could apparently increase the biomass of maize shoots by 23.0% and significantly increase the biomass of maize roots by 14.7%. The content of available Cu in the inoculated maize rhizospheric soil increased apparently and the Cu accumulated by the plants increased at the same time. Compared to the control, the concentration of copper in the maize shoots increased by 26.7% - 63.3%, and increased by 25.6% - 45.2% in the maize roots. The accumulated Cu by maize always aggregated in the root and was hard to transmit to the above-ground parts, the inoculation had a positive effect for Cu2+ transmission from root to shoots.

Related Dissertations

  1. Preliminary Study on Bacterial Diversity in Yunnan Non-ferrous Metals Mining,TD926.4
  2. Characterization of Mineral Phosphate-Solubilizing Bacterium K3 and Colonization under Different Soil,S144.9
  3. Cucumber Growth Promotion and Wilt Disease Suppression of Bacillus Subtilis SQR9 and Their Mechanisms,S436.421
  4. Establishment of Transgenic Soybean, Maize and Wheat Informationg Platform and Effect of Transgenic Soybean on Soil Microorganisms,S565.1
  5. The Composition of Pollutants and Degrading Bacterial Community Diversity in the Waste Drilling Fluid,X172
  6. Biodiversity of Bacteria and the Effect of Probiotics on It in Three Aquaculture Models,S917.1
  7. Effects of Grazing Intensity on Soil Physicochemical Properties and Bacteria Diversity for Stipa Baicalensis Steppe in Inner Mongolia,S812
  8. Pulp and paper effluent sediment metagenomic library construction and cellulase gene cloning and identification,Q78
  9. Identification of anammox granular sludge uncultured and culture preliminary study of bacterial diversity and new species of,X703
  10. Analysis of Bacterial Communities Diversity in Sediments of Lake Dongping,Q938.8
  11. Shandong inshore waters of bacterial diversity,S917.1
  12. Bactrian camel rumen bacterial diversity and metagenomic library construction and initial screening,S824
  13. Bacillus subtilis control sheath blight of maize,S435.131
  14. On Lin Shu’s Translation from the Perspective of Postcolonial Theory,I046
  15. Analysis of the Intestinal Microflora in Hepialus Gonggaensis Larvae,S567.35
  16. Military Colonization: The Military Administration by Germany Navy in the "Leased Tsiaochou" (1897-1914),K251
  17. Fine Arts in Manchukuo,J209.2
  18. The Biological Behavior of Human Fetal Liver-derived Stem Cells in Fah-/-Rag2-/- Mice,R657.3
  19. Glacier forefront soil bacterial diversity and its Relationship with Soil Properties,S154.3
  20. Urumqi River District temporal and spatial distribution of soil microorganisms,S154.3

CLC: > Environmental science, safety science > Environmental pollution and its prevention > Soil Contamination and Control
© 2012 www.DissertationTopic.Net  Mobile